Repression of Irs2 by let-7 miRNAs is essential for homeostasis of the telencephalic neuroepithelium.

Structural integrity and cellular homeostasis of the embryonic stem cell niche are critical for normal tissue development. In the telencephalic neuroepithelium, this is controlled in part by cell adhesion molecules and regulators of progenitor cell lineage, but the specific orchestration of these processes remains unknown. Here, we studied the role of microRNAs in the embryonic telencephalon as key regulators of gene expression. By using the early recombiner Rx-Cre mouse, we identify novel and critical roles of miRNAs in early brain development, demonstrating they are essential to preserve the cellular homeostasis and structural integrity of the telencephalic neuroepithelium. We show that Rx-Cre;DicerF/F mouse embryos have a severe disruption of the telencephalic apical junction belt, followed by invagination of the ventricular surface and formation of hyperproliferative rosettes. Transcriptome analyses and functional experiments in vivo show that these defects result from upregulation of Irs2 upon loss of let-7 miRNAs in an apoptosis-independent manner. Our results reveal an unprecedented relevance of miRNAs in early forebrain development, with potential mechanistic implications in pediatric brain cancer.

A Complex Code of Extrinsic Influences on Cortical Progenitor Cells of Higher Mammals.

Development of the cerebral cortex depends critically on the regulation of progenitor cell proliferation and fate. Cortical progenitor cells are remarkably diverse with regard to their morphology as well as laminar and areal position. Extrinsic factors, such as thalamic axons, have been proposed to play key roles in progenitor cell regulation, but the diversity, extent and timing of interactions between extrinsic elements and each class of cortical progenitor cell in higher mammals remain undefined. Here we use the ferret to demonstrate the existence of a complex set of extrinsic elements that may interact, alone or in combination, with subpopulations of progenitor cells, defining a code of extrinsic influences. This code and its complexity vary significantly between developmental stages, layer of residence and morphology of progenitor cells. By analyzing the spatial-temporal overlap of progenitor cell subtypes with neuronal and axonal populations, we show that multiple sets of migrating neurons and axon tracts overlap extensively with subdivisions of the Subventricular Zones, in an exquisite lamina-specific pattern. Our findings provide a framework for understanding the feedback influence of both intra- and extra-cortical elements onto progenitor cells to modulate their dynamics and fate decisions in gyrencephalic brains.

Regulation of cerebral cortex size and folding by expansion of basal progenitors.

Size and folding of the cerebral cortex increased massively during mammalian evolution leading to the current diversity of brain morphologies. Various subtypes of neural stem and progenitor cells have been proposed to contribute differently in regulating thickness or folding of the cerebral cortex during development, but their specific roles have not been demonstrated. We report that the controlled expansion of unipotent basal progenitors in mouse embryos led to megalencephaly, with increased surface area of the cerebral cortex, but not to cortical folding. In contrast, expansion of multipotent basal progenitors in the naturally gyrencephalic ferret was sufficient to drive the formation of additional folds and fissures. In both models, changes occurred while preserving a structurally normal, six-layered cortex. Our results are the first experimental demonstration of specific and distinct roles for basal progenitor subtypes in regulating cerebral cortex size and folding during development underlying the superior intellectual capability acquired by higher mammals during evolution.

Non-invasive ventilation in obesity hypoventilation syndrome without severe obstructive sleep apnoea.

BACKGROUND: Non-invasive ventilation (NIV) is an effective form of treatment in patients with obesity hypoventilation syndrome (OHS) who have concomitant severe obstructive sleep apnoea (OSA). However, there is a paucity of evidence on the efficacy of NIV in patients with OHS without severe OSA. We performed a multicentre randomised clinical trial to determine the comparative efficacy of NIV versus lifestyle modification (control group) using daytime arterial carbon dioxide tension (PaCO2) as the main outcome measure. METHODS: Between May 2009 and December 2014 we sequentially screened patients with OHS without severe OSA. Participants were randomised to NIV versus lifestyle modification and were followed for 2 months. Arterial blood gas parameters, clinical symptoms, health-related quality of life assessments, polysomnography, spirometry, 6-min walk distance test, blood pressure measurements and healthcare resource utilisation were evaluated. Statistical analysis was performed using intention-to-treat analysis. RESULTS: A total of 365 patients were screened of whom 58 were excluded. Severe OSA was present in 221 and the remaining 86 patients without severe OSA were randomised. NIV led to a significantly larger improvement in PaCO2 of -6 (95% CI -7.7 to -4.2) mm Hg versus -2.8 (95% CI -4.3 to -1.3) mm Hg, (p<0.001) and serum bicarbonate of -3.4 (95% CI -4.5 to -2.3) versus -1 (95% CI -1.7 to -0.2 95% CI)  mmol/L (p<0.001). PaCO2 change adjusted for NIV compliance did not further improve the inter-group statistical significance. Sleepiness, some health-related quality of life assessments and polysomnographic parameters improved significantly more with NIV than with lifestyle modification. Additionally, there was a tendency towards lower healthcare resource utilisation in the NIV group. CONCLUSIONS: NIV is more effective than lifestyle modification in improving daytime PaCO2, sleepiness and polysomnographic parameters. Long-term prospective studies are necessary to determine whether NIV reduces healthcare resource utilisation, cardiovascular events and mortality. TRIAL REGISTRATION NUMBER: NCT01405976; results.

A restricted period for formation of outer subventricular zone defined by Cdh1 and Trnp1 levels.

The outer subventricular zone (OSVZ) is a germinal layer playing key roles in the development of the neocortex, with particular relevance in gyrencephalic species such as human and ferret, where it contains abundant basal radial glia cells (bRGCs) that promote cortical expansion. Here we identify a brief period in ferret embryonic development when apical RGCs generate a burst of bRGCs that become founders of the OSVZ. After this period, bRGCs in the OSVZ proliferate and self-renew exclusively locally, thereby forming a self-sustained lineage independent from the other germinal layers. The time window for the brief period of OSVZ bRGC production is delineated by the coincident downregulation of Cdh1 and Trnp1, and their upregulation reduces bRGC production and prevents OSVZ seeding. This mechanism in cortical development may have key relevance in brain evolution and disease.

Sueño saludable: evidencias y guías de actuación. Documento oficial de la Sociedad Española de Sueño / Healthy sleep: evidence and guidelines for action. Official document of the Spanish Sleep Society

La Sociedad Española de Sueño tiene como uno de sus principales objetivos la promoción de un sueño saludable en la población general y profesionales de la salud. El presente documento pretende realizar una revisión de la literatura científica actual sobre hábitos de sueño que sirva de fundamento para establecer unas recomendaciones generales y útiles para la población general española, en el contexto de un sueño saludable, e identificar aquellos principales retos en la investigación sobre hábitos de sueño. El desarrollo del documento se ha realizado por un equipo multidisciplinar de miembros de la Sociedad Española de Sueño integrado por expertos en medicina pediátrica del sueño, neurofisiología clínica, neumología, neurología, cronobiología, fisiología y psicología. Se ha procedido a una revisión de la bibliografía científica existente sobre hábitos de sueño en población general, y se han abordado los siguientes aspectos: estado actual de los hábitos de sueño en la población española; revisión genérica de la cantidad óptima de horas de sueño; impacto del entorno ambiental (ruido, temperatura, iluminación...), horarios de sueño, alimentación y deporte; y apartados específicos para niños y adolescentes, trabajadores a turnos y conducción de vehículos. De todos los aspectos abordados a lo largo de este documento, se concluyen unas recomendaciones generales finales que servirán de guía a la población general y profesionales de la salud, así como se discuten los principales retos ambientales y futuras direcciones de investigación (AU)

One of the main objectives of the Spanish Sleep Society is to promote healthy sleep in both the general population and in health professionals. This document aims to conduct a review of the current scientific literature on sleep habits that can serve as the basis on which to establish a set of general recommendations, regarding healthy sleep, for use by the general population in Spain as well as to identify the main challenges faced by research into sleep habits. The document has been developed by a multidisciplinary team made up of members of the Spanish Sleep Society who are experts in paediatric sleep medicine, clinical neurophysiology, pulmonology, neurology, chronobiology, physiology and psychology. The existing scientific literature dealing with sleep habits in the general population was reviewed, and the following aspects were addressed: the current state of sleep habits in the Spanish population; a generic review of the optimum number of hours of sleep; the impact of the environmental setting (noise, temperature, illumination, etc.), hours of sleep, diet and sport, together with several specific sections for children and teenagers, shift-workers and drivers of different vehicles. The conclusions from all the aspects addressed in this document have resulted in a set of final general recommendations that will serve as a guide for the general population and health professionals. Likewise, the principal environmental challenges and future lines of research are also discussed (AU)